Electric motor and method of making the same



April 1, 1939. E. F. HUBACKER ELECTRIC MOTOR AND METHOD OF MAKING THESAME Filed Jan. 8, 1937 2 Sheets-Sheet l Qiiiiiiiiiiiii I A ril 1 1,1939. E. F. HUBACKER I ELECTRIC MOTOR AND METHOD OF MAKING THE SAME 2Sheeis-Sheet 2 Filed Jan. 8, 1937 Patented Apr. 11, 1939' PATENT OFFICEELECTRIC MOTOR AND METHOD OF MAKING THE SAME Earl F. Hubacker, HighlandPark, Mich, assignor to Borg-Warner Corporation, a corporation ofIllinois Application January 8, 1937, Serial No. 119,588

21 Claims. (Cl. 172-38) This invention relates to electric motors andmethod of making the same and has particular reference to electricmotors for use in refrigerating systems of the "sealed uni type.

My invention contemplates an electric motor construction wherein therotor thereof is arranged within a gas-tight casing, which also enclosesa compressor element of the refrigerating system, with the motorwindings arranged externally of 10 said casing.

This invention has particular reference to improvements in electricmotors of the foregoing type wherein by virtue of certain novelfeatures, the flux losses and attendant inefficiency of motors of thistype as heretofore constructed have been eliminated so that electricmotors embodying the novel features hereinafter disclosed and of theforegoing type may be constructed to operate just as efficiently asmotors of the type now 2 commonly employed for operating compressorelements, of refrigerating systems.

A principal object of the invention is the provision of a new andimproved type of sealed motor compressor construction, particularlyadapted for 25 use in refrigerating systems.

Another object of the invention is the provision of a new and improvedform of a sealed motor compressor unit wherein the motor windings arearranged externally of a gas-tight casing which 30 encloses the motorrotor and a compressor element, and which sealed motor compressor unitis cheaper in construction and more efilcient in operation than units ofthe foregoing type heretofore known. a

35 Another object of the invention is the provision of a sealed motorcompressor unit wherein the compressor and the rotor of the motor arearranged within a gas-tight casing, with the motor windings arrangedexternally of such casing, and which casing is constructed in part of anon-conducting material, such as a moldable plastic.

Another object of the invention is to provide a method of constructingand assembling sealed 45 motor units of the foregoing type so thatsuchunits may be manufactured on a large scale production basis and at acost comparable to that of building other types of motors now commonlyemployed in refrigerating systems.

50 Other objects and advantages of the invention will be apparent from aconsideration of the following specification taken in conjunction-withthe accompanying drawings of which there are two (2) sheets, andwherein:

55 Fig. 1 is a diagrammatic view illustrating the application of asealed motor unit embodying my invention to a refrigerating system ofthe compressor-condenser-expander type; v

Fig. 2 is a vertical sectional view of the motor compressor unitillustrated in Fig. l and taken 5 generally along the line 2-4 thereof;

Fig. 3 is a horizontal sectional view taken in a plane along the line3-3 of Fig. 2, looking in the direction of the arrows;

Fig. 4 is a perspective view of a non-conducting or plastic insert andwhich forms a part of the gas-tight casing of the sealed motorcompressor unit;

Fig. 5 is a perspective view of a stack of laminations which forms apart of the gas-tight casin of the sealed motor unit;

Fig. 6 is a view similar to that of Fig. 2, but illustrating a modifiedform of construction;

Fig. '7 is a viewsimilar to that of Fig. 3 and illustrating a modifiedform of construction of the gas-tight casing, this figure illustratingthe appearance of a part of the casing at an intermediate state of themanufacture thereof and Fig. 8 is a view similar to that illustrated inFig. '7 but showing the appearance of a part of the gas-tight casing ata later step in the manufacture thereof.

In Fig. 1 there is illustrated the application of a sealed motorcompressor unit embodying my invention to a refrigerating system; suchsystem 80 being illustrated as comprising a sealed motor compressor unitIll, a condenser l2 and an evaporator il adaptedfor disposal in a heatinsulated compartment, and all of the elements of the system beingconnected in a closed cycle and the system being charged with a suitablerefrigerant. Preferably the circuit It for the motor of the unit Itincludes a thermally operated switch It which has a thermostatic element20 thermally associated with the evaporator element It so that thecompressor element of the unit it may be operated intermittently forsupplying refrigerant to the evaporator element It in order to maintainthe temperature thereof within certain predetermined limits, the supplyof refrigerant to the evaporator being under the control of a suitableregulating device, such as a float valve.

The sealed motor compressor unit I 0 comprises a compressor 2; shown inelevation and which compressor may be of the rotary type, and a 5 rotor24 arranged within a gas-tight casing 26, and a stator 20 including themotor windings 30, which are arranged externally of the casing 26. Thecasing 26, as illustrated in Fig. 2 comprises a metallic end plate 32,an intermediate nong metallic ring 34, a stator ring indicated generallyat 36, a second non-metallic ring 36, and a metallic end ring 46, all ofwhich parts are integrally connected so as to form a gas-tight shell,and a metallic end wall or bearing block 42 is fitted within themetallic end ring 46 and sealed thereto such as by welding so as toprovide a closed gas-tight casing or shell. The non-metallic rings 34and 36 are illustrated as being formed of a moldable plastic ornon-conducting material and may be bonded or otherwise suitably securedto the stator ring 36, the end plate 32 and the end ring 46. The bearingblock 42 has rigidly secured thereto an upstanding axle or shaft 44,which extends axially through the casing 26 and the end of which shaft44 projects through a central opening in the end plate 32 into a recesstherein, wherein a nut 46 is threadedly secured to such end of the shaft44 so as to assist in holding the parts of the casing 26 together. Therecess 48 in which the nut 46 is disposed may be closed by a couplingmember 56 to which a conduit 62 for the refrigerant medium is connected,it being contemplated that some provision be made for affordingcommunication between the recess 46 and the interior of the casing 26.Refrigerant compressed in the compressor 22 may be discharged in anysuitable manner into the interior of the casing 26 from whence it mayescape through an opening (not shown) in the wall thereof into therecess 46. Another conduit 54 may be connected to a passageway 56through the bearing block for supplying vaporous refrigerant to thecompressor 22.

The shaft 44 comprises an axle upon which the rotor 24 of the motor andan eccentric 66 of the compressor 22 may rotate, the rotor 24 of themotor being illustrated as carried by a sleeve 66 journaled upon theshaft 44 and which may be formed integrally with the eccentric 66. Athrust bearing may be provided between the eccentric 58 and the bearingblock 42 for taking the thrust of the rotor of the motor. The rotor 24of the motor may comprise a stack of laminations 62 secured together bya series of rivets 64 and which stack of laminations are press-fittedupon one end of the sleeve 66. The rotor 24 may be provided with aseries of eways extending therethrough so as to permit the transfer ofrefrigerant from one side of the rotor to the other.

The stator 26 of the motor includes the inner ring 36, the outer ring66, which rings are assem bled so as to form an integral unit and themotor windings 36. The outer ring 66 may comprise a stack of laminations63 secured together, such as by a series of rivets I6 and formed toprovide on the inner periphery thereof a series of radially extendlngslots 12 adapted for receiving the motor windings 36. The inner ring 36may comprise an annular series of stacks 14 of laminations I5 connectedtogether by complementary-shaped non-metallic or non-conducting insertsI6 and which inserts are adapted to be arranged opposite, or radially inline with the motor windings 36. The non-conducting inserts I6 may beformed of a plastic material and bonded to the stacks I4 of laminationsI6 so as to provide an integral gas-tight ring 36. The laminations I6 ofthe stacks I4 may be formed of silicon steel and are adapted to bearranged radially inwardly of the metal fingers I6 of the outer ring 66,which are disposed between the slots I2.

The laminations I6 for the stacks I4 of laminations may be formedseparately and then arranged in stacks. The inserts I6 may beindividually formed and together with the stacks I6 of laminations maybe arranged in a mold where the stacks I4 of laminations and the insertsI6 may be subjected to pressure and/or heat so as to bond thelaminations I6 of the stacks I4 and the inserts I6 together in order toprovide a gas-tight ring. Preferably the laminations I5 of the stacks I4are provided with plastic or sealing material between the faces thereofin order to insure the sealing of the laminations I5 of the stacks I4together. After the inner ring 36 is formed the outer periphery thereofand/or the inner periphery of the outer ring may be ground so that theinner ring can be press-fitted within inner periphery of the outer ring66. The inner ring 36 is to be so fitted to the outer ring 66 so thatthere is good contact between the stacks 14' of laminations and the.

inwardly extending fingers I6 of the laminations of the outer ring 66 inorder that good conductivity may be provided for the magnetic field.After the inner ring 36 and the outer ring 66 have been assembledtogether so as to form a unit, the inner periphery of the inner ring 36is ground so as to provide a surface which will be concentric with theaxis about which the stator 24 rotates so that a proper air gap may beprovided between the rotor 24 and the stator n The motor windings 36 arearranged in the slots I2 before the inner ring 36 is assembled with theouter ring 66 and after assembly of the inner and outer rings of thestator 26 and the motor windings 36, the same, together with thenon-metallic rings 34 and 36, the end plate 32 and the end ring 46, aresuitably secured together so as to form the gas-tight shell 26.

As the rotor 24 and the stator rings 36 and 66 are made up of stacks oflaminations of a suitable magnetic material such as silicon steel, asingle blank of metal may be utilized to form lamina for each of theseparts; that is, a single blank of metal may be stamped out to form alamina 66 for the outer stator ring 66, a lamina 62 for the rotor 24 andan annular lamina out of which the laminations I6 of the stack 14 areformed. This annular lamina, which would be the metal left over afterthe rotor lamina 62 and the lamina 69 for the outer stator ring 66 wereformed, could be utilized to form the laminations 16 of the stacks I4.This might be done by stamping out such annular lamina to definelaminations I6, such as illustrated in Fig. 5, which would have to bestacked and arranged along with the inserts I6 so as to make up the ring36, as previously described.

The annular lamina remaining after the lamina 62 of the rotor and thelamina 66 for the outer stator ring have been formed might be made in a.form such as that illustrated at 66 in Fig. 'I. It will be observed thatthe metal of the annular lamina 66 is continuous and that the lamina 66is formed to provide slots 62 which are bridged at the inner peripheryof the lamina 66 by a very small amount of metal indicated at 64. Thisconnecting portion 64 may be in the neighborhood of .025" thick and bedisposed inwardly with respect to the main body of the lamina 66. Theslots 62 formed in the lamina 66 are adapted to receive inserts 66 of anonconducting material such as a plastic and these inserts may be formedindividually.

A stator ring such as 36 and made up of a stack of laminations such asthose indicated at 66 may have the inserts 66 placed therein whenausascs a stack 01' laminations 80 are assembled in a mold or theinserts 86 may be formed by introducing a plastic material under heatand pressure into a mold in which a stack of laminations 80are'assembled. It is contemplated that the laminations 86 may be coatedwith a plastic or sealing material so that when the laminations 86 areassembled in a mold and the inserts 86 are formed and disposed in theslots 82, the entire stator ring including the laminations 82 and theinserts 86 would be bonded together so as to form a gas-tight ring.After the ring made up of the laminations 86 has been formed, the innerperiphery thereof. may be ground out to provide a ring such as thatillustrated in Fig. 8. Referring to Fig. 8, it will be observed, thatthe connecting portions 84 have been ground away so that the stator ringcomprises stacks of laminations alternately arranged with bars orinserts of plastic or non-conducting material and all of which areintimately bonded together. The configuration of the lamina I6 andinserts I6 is believed to produce a better joint between the metal andthe non-metallic material forming the inner stator ring.

Instead of forming the connecting portions 84 as illustrated in Fig. 7,the lamina 80 might be formed so that the inner periphery thereof wascylindrical and so that the slots 82 were of such a depth as to leaveonly a very small amount of metal bridging the slots; then, after theplastic material had been bonded to the stack of laminations to form aninnerstator ring, the entire inner periphery of such ring might beground down to such an extent as to grind away the metal or connectingportion, bridging the slots 82 or such metal or connecting portionbridging the slots might be cut, such as by a saw, so that'thecontinuity of themetal was interrupted and so that the inserts 82 wouldbe alternately arranged with the metal to form a continuous gas-tightring. This annular ring could then be assembled with the outer statorring in the manner as described in connection with the stator ring 86.

In Fig. 6 there is illustrated a modified form of. construction whereina casing or shell I26 is formed similar to the shell 26 except for theopen end thereof. ranged within a metallic end ring I48 which forms theend of the shell I26 and the ring I 46 projects beyond the end of thebearing block I42 so as to form an annular surface I48 to which astamped-end plate I46 may be secured, such as by welding. The bearingblock I42 is provided with a sleeve-like bearing member I44 in which ashaft I46 isjournaled. One end of the shaft I46 is secured to a sleeveI48 and the other end of the shaft I46 is extended to iorm an eccentricfor the compressor I22 which may be of the rotary type. The sleeve I48carries the rotor I24 and extends down below the top of a shell I23which is adapted for collecting oil therein and about the working partsof the rotary compressor.

In the case of the modification illustrated in Fig. 6 the stator I28 maycorrespond in construction to that of the stator 28 illustrated in Fig.2. The principal difference between the two modifications is that inthecase of modification illustrated in Fig. 6 the shaft I46 is supported bythe single bearing I44, which is mounted upon the bearing block I42 andsuch bearing is not directly connected with the top plate of the casingI26, whereas in the modification illustrated in Fig. 2 the shaft 44 iscon- A hearing block I42 is arnectedto the top and bottom walls of thecasing and hence is dependent upon the position of both of these membersin order to maintain and. establish its proper position. That is, in thecase of the modification illustrated in Fig. 2 the alignment of therotor 24 with the stator 28 is dependent upon the proper alignment ofthe shaft 44 which has two points of support, whereas the bearing I44 inthe modification illustrated in Fig. 6 has only one point of support.

It will be observed that'in both of the forms of inner stator rings asillustrated in Figs. 3 and 8, thejstator rings are made up of stacks oflaminations separated by inserts of non-conducting or plastic materialsecurely bonded thereto. It will also be observed that those parts ofthe casings 26 and I26 opposite the motor windings are formed of anon-conducting material such as plastic material in order to prevent anymagnetic losses through these parts of the casing.

The plastic or non-conducting material should be resistant to oil andthe refrigerant medium and also one which is capable of withstanding thetemperatures and pressures which prevail within the casings 26 and I26in order to prevent the leakage of refrigerant. Thosewportions of thewalls of the casing 26 and I26 formed of plastic material preferablyshould be bonded to the metallic parts of the casing. Examples ofplastic material which may be used are glass,

phenolic molding compounds and inorganic cold molded compounds.

While the invention has been described with some detail, it is to beunderstood that the description is for the purpose of illustration onlyand is not definitive of the limits of the inventive idea. The right isreserved to make such changes in the details of construction andarrangement of parts as will fall within the purview of the attachedclaims.

I claim:

1. Electric motor construction comprising an annulus of laminations ofmagnetic material forming an outer stator ring, an inner stator ringarranged within said outer stator ring, said rings being formed toprovide an annular series of slots therebetween, said inner stator ringbeing formed of non-conducting material and laminations of magneticmaterial bonded together so as to form'a gas-tight ring, said inner ringconstituting a part of a gas-tight casing, a motor rotor arranged withinsaid casing, and motor windings arranged in said slots and disposedexternally of said casing.

2. Electric motor construction comprising an annulus of laminations ofmagnetic material forming an outer stator ring, an inner stator ringarranged within said outer stator ring, said rings being formed toprovide an annular series of slots therebetween, said inner stator ringbe- .ing formed of plastic material and laminations constituting a partof a gas-tight ring arranged inwardly of said motor windings and saidring being formed in part of a non-conducting material bonded to theinner extremities oi said. projections, said gas-tight ring constitutinga part of a sealed casing, and a motor rotor arranged within saidcasing.

4. In electric motor construction, a stator comprising an annulus oflaminations of magnetic material and having inwardly extending laminatedsections of magnetic material arranged to define an annular series ofslots, motor windings arranged in said slots, the inner portion of saidsections comprising a part of a gas-tight ring which is formed in partof a plastic material bonded to said laminations, said gas-tight ringforming a part of a sealed casing which is arranged inwardly of saidmotor windings and a motor rotor arranged within said gas-tight casing.

5. In electric motor construction, a stator comprising an annulus oflaminations of magnetic material and having inwardly extending laminatedsections of magnetic material arranged to define an annular series ofslots, motor windings arranged in said slots, the inner portion of saidsections comprising a part of a gas-tight ring which is formed in partof a plastic material bonded to said laminations, said gas-tight ringforming a part of a sealed casing which is arranged inwardly of saidmotor windings and a motor rotor arranged within said gas-tight casing,those portions of said gas-tight casing disposed opposite to said motorwindings being formed of plastic material 6. In electric motorconstruction, a stator comprising an annulus of laminations of magneticmaterial provided with inwardly extending laminated projections arrangedto define an annular series of slots, motor windings arranged in saidslots, the inner extremities of said projections constituting a part ofa gas-tight ring arranged inwardly of said motor windings and said ringbeing formed in part of a non-conducting material bonded to the innerextremities of said projections, said gas-tight ring constituting a partof a sealed casing, and a motor rotor arranged within said casing, thoseportions of said sealed casing opposite said motor windings being formedof a non-conducting material.

7. Electric motor construction comprising a gas-tight ring adapted toform a part of a gastight casing, said ring comprising an annular seriesof spaced stacks of laminations of magnetic material connected by bodiesof non-conductin material, said ring forming a part of a sealed casing,a motor rotor arranged within said casing, an annulus of laminationsdisposed outwardly of said ring and adapted to provide in conjunctiontherewith an annular series of slots, and motor windings arranged insaid slots and disposed externally of said casing.

8. In electric motor construction, a gas-tight ring comprisingalternately arranged sections of laminations of magnetic material and ofplastic material bonded together, said ring forming a part of a sealedcasing, a motor rotor arranged within said casing, motor windingsarranged externally of said ring, and means associated with said motorwindings and with said laminations of said ring to provide a path forthe magnetic field.

'9. In electric motor construction, a gas-tight rin g formed ofnon-conducting material and laminations of ma netic material bondedtogether, said ring forming a part of a gas-tight casing, a

motor rotor arranged within said casing, motor windings arrangedexternally of said ring, and means operatively associated with saidwindings and the laminations or said ring, so as toprovid'e a metallicpath for the magnetic field.

10. In electric motor construction, a gas-tight ring formed of plasticmaterial and laminations of magnetic material bonded together, said ringforming a part of a sealed casing, a motor rotor arranged within saidcasing, motor windings arranged externally of said ring, and meansincluding laminations of magnetic material operatively associated withsaid windings and said laminations of said ring to provide a metallicpath for the magnetic field of said windi gs.

11. In electric motor construction, a gas-tight ring comprising segmentsof laminations of magnetic material separated by and bonded to segmentsof a non-conducting material, said ring forming a part of a sealedcasing, a motor rotor arranged within said casing, motor windingsarranged'externally of said ring, and means including laminations ofmagnetic material operatively associated with said motor windings andsaid laminations of said ring to provide a metallic path for themagnetic field of said windings.

12. In electric motor construction, a gas-tight ring comprising segmentsof laminations of magnetic material separated by and bonded to segmentsof a plastic material, said ring forming a part of a sealed casing, amotor rotor arranged within said casing, motor windingsarrangedexternally of said ring, and means including laminations of magneticmaterial operatively associated with said motor windings and saidlaminations 01 said ring to provide a metallic path for the magneticfield of said windings.

13. The method of forming a stator ring for a sealed motor wherein thewindings are arranged externally of a sealed casing which comprisesforming a plurality of laminations of magnetic material, forming a stackof said laminations, bonding plastic material to said stack oflaminations externally thereof, and removing metal from the inside ofsaid stack so as to interrupt the continuity of the laminations on theinnerperiphery of said stack.

14. The method of forming a stator ring for a sealed lrotor wherein thewindings are arranged externally of a sealed casing which consists informing a series of annular laminations having radial projectionsdefining slots therebetween, forming a stack of said laminations,bonding a non-conducting material in said slots, and grinding away theinner periphery of said stack so as to expose said non-conductingmaterial to the inside of said stack.

15. The method of forming a stator ring for a sealed motor wherein thewindings are arranged externally of a sealed casing which consists informing a stack oi laminations of magnetic material provided withexternal projections defining slots, bonding a plastic material to saidstack and within said slots, and cutting and magnetic material away fromsaid stack and on the inside thereof opposite said slots so as tointerrupt the continuity of said laminations.

16. The method of forming a stator ring for a sealed motor wherein thewindings are arranged externally of a sealed casing which consists informing stacks of plastic material and of laminations of magneticmaterial, alternately arranging stacks of laminations and of plasticmaterial so as to define a ring, and bonding said amazes fiterialtogether so as to provide. a gas-tight 1'1. The method of forming astator ring for a sealed motor wherein the windings are arrangedexternally of a sealed casing which comprises forming a plurality oflaminations of magnetic material, forming said laminations into a stack,bonding said stack of laminatioiis together and removing metal fromlaminations on the inside of said stack.

18. Electric motor construction comprising a stack of laminations oimagnetic material forming an outer stator ring, an inner stator ringarranged within said outer ring, said rings being formed to provide aseries of motor winding slots therebetween, said inner ring being formedof plastic material and of laminations of magnetic material bondedtogether so as to form a gastight ring, said ring constituting a part ofa sealed casing, a motor rotor operatively arranged within said casingand motor windings arranged in said slots and exposed to the air outsideof said 19. Electric motor construction comprising a stack oflaminations of magnetic material forming an outer stator ring, an innerstator ring ara motor rotor operatively arranged within said casing andmotor windings arranged in said slots and exposed to the air outside ofsaid casing.

20. Electric motor construction comprising a stack of iaminations ormagnetic material forming an outer stator ring, an inner stator ringarranged within said outer ring, said rings beingv stator ring formed ornonconducting material and laminations of magnetic material bonded together so as to form a gas-tight ring, motor windings arrangedexternally of said ring, said ring constituting a part of a sealedcasing which includes sections of nonconductlng material arrangedopposite the ends of said motor windings. means for securing saidsections and said ring together, a motor rotor operatively arrangedwithin said casing and means operatively associated with said motorwindings and with said laminations oi said ring to provide a path forthe mag-v netic held of said win EARL i". ,HUBAOKIR.

